Site autologged out even if there is activity in custom form

I had a large form which auto logged even though there was activity in the form. We need misc/form.js to bind "formUpdated" to form inputs and trigger it on any change in the form. This js is not added to all forms by default.

So I had to add the code below in my form callback function to add it.

drupal_add_library('system', 'drupal.form');

Shouldn't we add this in the documentation/README.txt about this?